Aren't there several? There's deflection as the queen has no squares to move to which don't lose the Rook on d6. There's discovered check as in 2. Rxc4. There's also a winning pin after 1. .. Bxd5 2. Rd7. The last one isn't so easy to spot but you have to know it's there before playing Nd5.
Technical questions regarding Openings, Middlegames, Endings etc.
White's a piece up and needs to find a move that saves the rook on c7 and stops Black drawing by 1... Qd2+ 2.Kb2 Qb4+, as well as the observations made by Roger.
You've only given half the combination showing that Nd5 does leave White a piece up. The full sequence is:
Ian Thompson wrote: ↑Sat Dec 02, 2017 12:30 pmWhite's a piece up and needs to find a move that saves the rook on c7 and stops Black drawing by 1... Qd2+ 2.Kb2 Qb4+, as well as the observations made by Roger.
You've only given half the combination showing that Nd5 does leave White a piece up. The full sequenceWell, that's as far as the solution goes, according to tactics.chessbase.com
The Queen and Bishop are both attacked, so to defend both the Queen has to go to h6,h5 or h4. On h4, there's also a threat of Qxf2, so h4 would appear the best square. That's very superficial analysis, but it's enough to choose Qh4 with little time used.
I suppose you have to spot the potential mate on c1 and use it to put the sequence of moves together. Some players are just better at that sort of thing than others. It helps if you are able to play the rest of the game in a style that creates these opportunities.
It's a nice deflection sacrifice and you have to see that Qxh6 can be met by Bxd2.
It's Botvinnik v Kan from 1930.
According to an engine, Kan got a bad game not with .. b6, but by following it up with .. d6 .
It's more that the resulting structure where White has played d5, Black responds with .. e5 isn't very good.
Instead you can keep the pawn back at d7 and get positions like this.